1. Field of the Invention
The present invention relates generally to the field of explosion protection systems, and more particularly to an explosion suppressant dispersion nozzle for connection to a pressurized suppressant vessel for discharging suppressant material to a protected zone or room.
2. Description of the Prior Art
Many industrial and commercial areas are equipped with explosion protection systems for preventing and extinguishing explosions in protected zones or rooms. These explosion protection systems are typically designed to insure a nearly simultaneous release of explosion suppressant material into the protected zones from several spaced locations to quickly prevent or extinguish an explosion.
As alluded to in U.S. Pat. No. 5,031,701, which is incorporated herein by reference thereto, the mechanics of delivering an effective amount of a suppressant to an incipient explosion and in a uniform dispersion pattern has lagged behind the technology of detecting the onset of an explosion as a function of pressure rise in a protected zone. Pressure detection techniques are now so sensitive that detectors are capable of responding to sudden or increase in pressure in only a few milliseconds. However, in order to suppress an explosion before the pressure rise starts to increase along the vertical portion of the exponential curve, suppressant must be uniformly delivered to the threatened area during the initial, flatter part of the pressure rise curve.
One type of prior art explosion protection system includes a plurality of pressurized suppressant storage vessels spaced throughout a protected zone. Each storage vessel includes a rupture disc disposed across the discharge end of the storage vessel for sealing the pressurized suppressant material in the storage vessel, a sensor and control device for sensing the presence of an incipient explosion in the protected zone, an initiator or detonator responsive to the sensor and control device for rupturing the rupture disc in response to the detection of an incipient explosion, and a nozzle for dispersing the suppressant material throughout the protected zone.
The nozzles on these prior art explosion protection systems typically include a plurality of orifices, holes and/or windows for discharging suppressant from all sides of the nozzle. However, prior art nozzles are not optimally designed to disperse suppressant material throughout a protected zone in the most efficient and effective manner.
For example, it is advantageous for an explosion suppression dispersion nozzle to discharge suppressant in a hemispherical pattern so that substantially equal amounts of the suppressant reaches all points equidistant from the nozzle at essentially the same time. This allows for the most effective suppression of an explosion no matter where it occurs in the protected zone while also permitting the most efficient placement of the nozzles.
Prior art nozzles have not in fact been of optimal design for achieving a preferred hemispherical discharge pattern because the orifices, holes and/or windows that have been provided did not cooperate in the most efficient manner to assure substantially unimpeded, rapid delivery of suppressant while at the same time providing a desired hemispherical suppressant pattern at the protected site. FIG. 3 of the drawings appended hereto illustrates the discharge pattern of a typical prior art explosion suppressant discharge nozzle. As illustrated, a larger proportion of the suppressant is discharged from the tip and immediate sides of the nozzle than is discharged in the zones between the tip and sides of the nozzle. Therefore, the resultant non-uniform discharge pattern is not as effective as desired in suppressing explosions that originate in the area that has been assigned to be protected by a respective explosion protection unit.
It is also advantageous to achieve a desired discharge pattern without excessively diminishing the discharge rate of the suppressant out of the nozzle. For example, a perfectly hemispherical discharge pattern is not as beneficial if the discharge velocity of the suppressant is so low that the suppressant is not rapidly and uniformly delivered to protected points remote from the nozzle.
Prior art explosion suppression dispersion nozzles do not achieve a high discharge rate because the nozzles include orifices, holes, and/or windows having edges that extend nearly perpendicular to the longitudinal axis of the nozzle. These edges interfere with the flow of suppressant out of the nozzle and thus reduce the discharge rate of the suppressant. This of course reduces the effective discharge range of the nozzle. As illustrated in FIG. 3, these edges cause suppressant material to be discharged a long distance from the nozzle at certain points and only a short distant at other points. Again, this results in a non-hemispherical discharge pattern that is not as efficient in suppressing an explosion than would be the case in a more hemispherical suppressant pattern.
Since prior art dispersion nozzles have not achieved optimal suppressant discharge patterns while maintaining high discharge rates, it has been difficult to determine where the suppressant units should be positioned relative to one another to adequately protect a selected area. To remedy these deficiencies, it has been the practice to equip explosion protection systems with a sufficient number of individual suppressant delivery units to provide adequate overlapping of discharge patterns from adjacent units. It can be readily appreciated that adding extra, overlapping storage vessels and nozzles needlessly increases the costs of an explosion protection system.